Men with short index fingers and long ring fingers are on average nicer towards women, according to research in the US.
Apparently this happens because the men have been exposed to hormones in their mother’s womb.
The findings of the study at McGill University might help explain why these men tend to have more children.
Men’s index fingers are generally shorter than their ring fingers. The difference is less pronounced in women.
Previous research has found that digit ratio, defined as the second digit length divided by the fourth digit length, is an indication of the amount of male hormones, mainly testosterone, someone has been exposed to as a fetus.
And the smaller the ratio, the more male hormones. The latest study suggests that this has an impact on how adult men behave, especially with women.
“It is fascinating to see that moderate variations of hormones before birth can actually influence adult behaviour in a selective way,” says Simon Young, a McGill Emeritus Professor in Psychiatry and coauthor of the study.
Men with smaller ratios are more likely to listen to women attentively, smile and laugh, compromise or compliment the other person.
These men are also less quarrelsome with women than with men.
However, the men with larger ratios are quarrelsome with both men and women.
For women though, digit ratio variation doesn’t seem to predict how they behaved.
The study, showing a link between a biological event in fetal life and adult behaviour, was published in the journal Personality and Individual Differences.
NOW WATCH: Briefing videos
Business Insider Emails & Alerts
Site highlights each day to your inbox.